Nova Cannons have ranges up to 40VU. Voidship weapons can be fired up to twice their range. Thus, Nova Cannons can be fired up to 80VU.
Have I missed something? Errata, secret rules hidden in a black box at the other end of the book, anything like that? Allowing these things to fire at roughly four times the range of the longest-ranged macrobatteries seems like a little much to me, especially since they trade the usual -60 penalty for firing at any ship using evasive maneuvers for a mere -20/-30.
Also, because I have this weird mental disorder where I can't post on FFG without pointing out something silly:
20 Nova Cannon shells = -20 Acquisition
Brand new (Mars Pattern) Nova Cannon + 20 Nova Cannon shells = -20 Acquisition